How to create Sub on dynamically created ComboBox in VBA? - vba

Question

I am very new to excel programming and VBA. I am stuck at a point where I have random number of dynamically created combo boxes (ComboBox1, ComboBox2.... ComboBoxN).
I need to implement a functionality where if I select a value in the ComboBox[i] (where i can be any random number between 1 to N), then it should trigger an event that will populate values in ComboBox[i+1].
How do I write a Sub for this? Is there any other way to implement this if not in a Sub?

Answer 1

In order to create a group events you'll need a custom class to capture the events ( ObjectListener ), public variable to keep the class references alive (usually a collection or array - ComboListener ) and a Macro to fill the collection ( AddListeners_ComboBoxes ).
Call the AddListeners_ComboBoxes Macro from the Workbook_Open(). You will need call AddListeners_ComboBoxes again if the code breaks.
Standard Module
Public ComboListener As Collection
Sub AddListeners_ComboBoxes()
Dim ws As Worksheet
Dim obj As OLEObject
Dim listener As ObjectListener
Set ComboListener = New Collection
For Each ws In Worksheets
For Each obj In ws.OLEObjects
Select Case TypeName(obj.Object)
Case "ComboBox"
Set listener = New ObjectListener
Set listener.Combo = obj.Object
ComboListener.Add listener
End Select
Next
Next
End Sub
Class ObjectListener
Option Explicit
Public WithEvents Combo As MSForms.ComboBox
Private Sub Combo_Change()
MsgBox Combo.Name
Select Case Combo.Name
Case "ComboBox2"
ActiveSheet.OLEObjects("ComboBox3").Object.ListIndex = 1
End Select
End Sub

Answer 2

As an alternative to the "Class" approach shown by Thomas Inzina here's a "less structured" approach:
Private Sub ComboBox1_Change()
PopulateCombo 2
End Sub
Private Sub ComboBox2_Change()
PopulateCombo 3
End Sub
Private Sub ComboBox3_Change()
PopulateCombo 4
End Sub
Private Sub ComboBox4_Change()
PopulateCombo 1 '<--| will "last" combobox populate the "first" one?
End Sub
Private Sub PopulateCombo(cbNr As Long)
With ActiveSheet.OLEObjects("ComboBox" & cbNr) '<--| reference the combobox as per the passed number
.ListFillRange = "Sheet1!J1:J10" '<--| populate it with "Sheet1" worksheet range "A1:A10"
.Object.ListIndex = 1 '<--| select its first item
End With
End Sub